MANILA (Reuters) - The Philippine environment minister said she has been given the green light by President Rodrigo Duterte to work with communist rebel fighters to help rehabilitate and develop the country's mining areas.

The decades-long conflict between the New People's Army (NPA) rebels and the Philippine government has killed more than 40,000 people. Earlier this month the NPA agreed to a temporary truce with government, the first joint ceasefire since November 1986.

Environment and Natural Resources Secretary Regina Lopez last month ordered the closure of more than half the nation's mines to protect water resources, a bold step backed by Duterte, who has said the Philippines can survive without mining.

Lopez, an environmentalist-turned-regulator, said her unorthodox plan to work with the rebels has his backing.

"What I've seen with the NPA, they just really want to get people out of poverty, they're really not bad people," Lopez told reporters on Thursday. "We might have a situation where miners work with the NPA. We must come from the same page."

Jose Maria Sison, the founder and leader of the Communist Party of the Philippines who lives in exile in Utrecht, welcomed Lopez' desire "to work with the NPA for peace and development".

"It is directly related to the environment, agrarian reform and rural development now being negotiated under the substantive item," he said in a Facebook post, inviting her to attend the next round of peace talks, brokered by Norway, in the Netherlands next month.

Lopez said she's initially looking at working with NPA rebels to develop a mining province in southern Mindanao island, and had asked Duterte's permission at a recent cabinet meeting and "he gave a go-ahead."

Duterte's spokesman, Ernesto Abella, said however "that needs to be verified" when asked to confirm the plan.

Miners were unsure whether Lopez's strategy would work.

Mining contracts "are granted by the government, not by the NPAs. So, in what capacity could we work with the NPAs? I don't know," Dante Bravo, president of Global Ferronickel Holdings Inc, told Reuters. Global Ferronickel is the Philippines' No. 2 nickel ore producer.

The Philippine Army did not immediately respond to a request for comment.

Lopez waged a crackdown on the Philippine mining sector shortly after taking office in June last year. In February, she ordered the closure of 22 of the Southeast Asian nation's 41 mines and later cancelled dozens of contracts for undeveloped mines.

Duterte backed Lopez's mining crackdown, himself angered by years of environmental harm he said miners have caused. Late on Wednesday, he reiterated his support for Lopez, who has said she wants the country to be "mine-free".

"I asked how can we do that? We have to amend the law. There's a mining law which allows mining," Duterte said.

"But I agree with Gina," Duterte said, calling the minister by her nickname.

Duterte reappointed Lopez this week after lawmakers deferred a decision to confirm or reject her appointment before Congress went into recess from March 18. Hearings on her confirmation resume on May 2.